全文获取类型
收费全文 | 1070篇 |
免费 | 40篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 44篇 |
妇产科学 | 11篇 |
基础医学 | 104篇 |
口腔科学 | 21篇 |
临床医学 | 73篇 |
内科学 | 275篇 |
皮肤病学 | 6篇 |
神经病学 | 45篇 |
特种医学 | 319篇 |
外科学 | 59篇 |
综合类 | 24篇 |
预防医学 | 44篇 |
眼科学 | 7篇 |
药学 | 77篇 |
中国医学 | 1篇 |
肿瘤学 | 15篇 |
出版年
2021年 | 7篇 |
2018年 | 6篇 |
2015年 | 6篇 |
2013年 | 12篇 |
2011年 | 7篇 |
2010年 | 11篇 |
2009年 | 15篇 |
2008年 | 6篇 |
2007年 | 22篇 |
2006年 | 12篇 |
2005年 | 7篇 |
2002年 | 7篇 |
2001年 | 7篇 |
1999年 | 12篇 |
1998年 | 51篇 |
1997年 | 44篇 |
1996年 | 67篇 |
1995年 | 48篇 |
1994年 | 42篇 |
1993年 | 49篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 17篇 |
1989年 | 40篇 |
1988年 | 37篇 |
1987年 | 33篇 |
1986年 | 34篇 |
1985年 | 43篇 |
1984年 | 20篇 |
1983年 | 27篇 |
1982年 | 33篇 |
1981年 | 33篇 |
1980年 | 18篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 29篇 |
1976年 | 22篇 |
1975年 | 15篇 |
1969年 | 4篇 |
1965年 | 5篇 |
1964年 | 4篇 |
1963年 | 7篇 |
1959年 | 11篇 |
1958年 | 28篇 |
1957年 | 28篇 |
1956年 | 33篇 |
1955年 | 29篇 |
1954年 | 28篇 |
1949年 | 17篇 |
1948年 | 13篇 |
排序方式: 共有1132条查询结果,搜索用时 15 毫秒
61.
62.
63.
RS de Vreeze D de Jong IH Tielen HJ Ruijter PM Nederlof RL Haas F van Coevorden 《Modern pathology》2009,22(2):223-231
Almost all primary retroperitoneal liposarcomas can be classified as well-/dedifferentiated liposarcoma. Rarely, however, primary retroperitoneal liposarcoma is classified as myxoid/round cell liposarcoma, based on the presence of myxoid areas and vascular crow's feet pattern, which has resulted in a debate on the classification of liposarcoma in the retroperitoneum. Genetically, myxoid/round cell liposarcoma and well-/dedifferentiated liposarcoma are different diseases. Myxoid/round cell liposarcoma is characterized by a translocation causing FUS-CHOP or EWSR1-CHOP fusion, whereas well-/dedifferentiated liposarcoma is characterized by an amplification of the 12q13-15 region, including MDM2 and CDK4 genes. As myxoid/round cell liposarcoma is highly radio- and chemosensitive, differentiation between subtypes is important to optimize treatment. We studied whether primary retroperitoneal liposarcomas diagnosed as myxoid/round cell liposarcoma represent molecularly true myxoid/round cell liposarcoma or are histopathological mimics and represent well-/dedifferentiated liposarcoma. Primary retroperitoneal myxoid/round cell liposarcoma (n=16) were compared to primary extremity myxoid/round cell liposarcoma (n=20). Histopathological and immunohistochemical features were studied. Amplification status of the 12q13-15 region was studied using a multiplex ligation-dependent probe amplification analysis, and FUS-CHOP or EWS-CHOP translocations were studied using RT-PCR. In primary retroperitoneal myxoid/round cell liposarcoma, MDM2 and CDK4 staining was both positive in 12 of 15 cases. In primary extremity myxoid/round cell liposarcoma, MDM2 was negative in 18/20 and CDK4 was negative in all cases. Multiplex ligation-dependent probe amplification showed the amplification of 12q13-15 region in 16/16 primary retroperitoneal myxoid/round cell liposarcomas and in 1/20 primary extremity myxoid/round cell liposarcomas. Translocation was present in all (18/18) primary extremity myxoid/round cell liposarcomas, but absent in all primary retroperitoneal myxoid/round cell liposarcomas. On the basis of immunohistochemical and molecular characteristics, apparent primary retroperitoneal myxoid/round cell liposarcoma can be recognized as well-/dedifferentiated liposarcoma with morphological features mimicking myxoid/round cell liposarcoma. In these cases, treatment should probably be specifically designed as for well-/dedifferentiated liposarcoma. Moreover, finding of myxoid/round cell liposarcoma translocations in a retroperitoneal localization is highly suggestive of metastasis and should prompt search for a primary localization outside the retroperitoneum. 相似文献
64.
65.
66.
67.
68.
Dunnick NR; Svetkey LP; Cohan RH; Newman GE; Braun SD; Himmelstein SI; Bollinger RR; McCann RL; Wilkinson RH Jr; Klotman PE 《Radiology》1989,171(1):219-222
Intravenous digital subtraction renal angiography (DSRA) has been compared with conventional angiography only in small, selected series of hypertensive patients. The authors prospectively examined with intravenous DSRA 94 patients at increased risk for renovascular hypertension and compared these studies with conventional angiography. A stenosis of at least one main renal artery was identified with intravenous DSRA in 22 patients and confirmed in 20 patients. No significant stenoses were seen with conventional angiography in any of the 64 patients in whom lesions were not seen with intravenous DSRA. Since inadequate DSRA studies were considered positive for renal artery stenosis, the sensitivity of intravenous DSRA was 100% (25 of 25); specificity, 93% (64 of 69); positive predictive value, 83% (25 of 30); and negative predictive value, 100% (64 of 64). The authors conclude that intravenous DSRA is a sensitive test for identifying stenosis of the main renal arteries and is appropriate to use as a screening test among patients at increased risk for renovascular hypertension. 相似文献
69.
One in eight Universities Central Council on Admissions (UCCA) applications for admission to St Mary's Hospital Medical School in 1986 were in due course recirculated to the four short-listers, being seen again either by the same short-lister or by another short-lister. Intrarater reliabilities were high, not only for measures of educational achievement, but also for the more subjective assessments. Interrater reliabilities were more variable, being very high for educational achievement, but rather lower for the more subjective items, and being lowest for the assessment of 'Interests', suggesting divergence between short-listers' perceptions of the terms. Nevertheless, all reliabilities were sufficiently high to justify the continued use of these criteria during selection. 相似文献
70.
Focal Adhesion Kinase Is Important for Fluid Shear Stress‐Induced Mechanotransduction in Osteoblasts
Suzanne RL Young Rita Gerard‐O'Riley Jae‐Beom Kim Fredrick M Pavalko 《Journal of bone and mineral research》2009,24(3):411-424
Mechanical loading of bone is important for maintenance of bone mass and structural stability of the skeleton. When bone is mechanically loaded, movement of fluid within the spaces surrounding bone cells generates fluid shear stress (FSS) that stimulates osteoblasts, resulting in enhanced anabolic activity. The mechanisms by which osteoblasts convert the external stimulation of FSS into biochemical changes, a process known as mechanotransduction, remain poorly understood. Focal adhesions are prime candidates for transducing external stimuli. Focal adhesion kinase (FAK), a nonreceptor tyrosine kinase found in focal adhesions, may play a key role in mechanotransduction, although its function has not been directly examined in osteoblasts. We examined the role of FAK in osteoblast mechanotransduction using short interfering RNA (siRNA), overexpression of a dominant negative FAK, and FAK?/? osteoblasts to disrupt FAK function in calvarial osteoblasts. Osteoblasts were subjected to varying periods oscillatory fluid flow (OFF) from 5 min to 4 h, and several physiologically important readouts of mechanotransduction were analyzed including: extracellular signal‐related kinase 1/2 phosphorylation, upregulation of c‐fos, cyclooxygenase‐2, and osteopontin, and release of prostaglandin E2. Osteoblasts with disrupted FAK signaling exhibited severely impaired mechanical responses in all endpoints examined. These data indicate the importance of FAK for both short and long periods of FSS‐induced mechanotransduction in osteoblasts. 相似文献